Thursday, December 11, 2008

How To Performing Clear Screen (CLS) in a Console Application

Some non-Microsoft versions of C++ provide a clrscr function for clearing the screen in a DOS application. However, there is no Win32 Application Programming Interface (API) or C-Runtime function that will perform this function.

To accomplish this task for a Win32 console application, use one of the following methods:
  • Use a system function.
  • Write a function that will programmatically clear the screen.
These methods are described in the following "More Information" section.
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Use a system function

#include 

void main()
{
system("cls");
}

Write a function that will programmatically clear the screen

The following function clears the screen:
 /* Standard error macro for reporting API errors */
#define PERR(bSuccess, api){if(!(bSuccess)) printf("%s:Error %d from %s \
on line %d\n", __FILE__, GetLastError(), api, __LINE__);}

void cls( HANDLE hConsole )
{
COORD coordScreen = { 0, 0 }; /* here's where we'll home the
cursor */
BOOL bSuccess;
DWORD cCharsWritten;
CONSOLE_SCREEN_BUFFER_INFO csbi; /* to get buffer info */
DWORD dwConSize; /* number of character cells in
the current buffer */

/* get the number of character cells in the current buffer */

bSuccess = GetConsoleScreenBufferInfo( hConsole, &csbi );
PERR( bSuccess, "GetConsoleScreenBufferInfo" );
dwConSize = csbi.dwSize.X * csbi.dwSize.Y;

/* fill the entire screen with blanks */

bSuccess = FillConsoleOutputCharacter( hConsole, (TCHAR) ' ',
dwConSize, coordScreen, &cCharsWritten );
PERR( bSuccess, "FillConsoleOutputCharacter" );

/* get the current text attribute */

bSuccess = GetConsoleScreenBufferInfo( hConsole, &csbi );
PERR( bSuccess, "ConsoleScreenBufferInfo" );

/* now set the buffer's attributes accordingly */

bSuccess = FillConsoleOutputAttribute( hConsole, csbi.wAttributes,
dwConSize, coordScreen, &cCharsWritten );
PERR( bSuccess, "FillConsoleOutputAttribute" );

/* put the cursor at (0, 0) */

bSuccess = SetConsoleCursorPosition( hConsole, coordScreen );
PERR( bSuccess, "SetConsoleCursorPosition" );
return;
}

APPLIES TO
  • Microsoft Win32 Application Programming Interface, when used with:
    • Microsoft Windows NT 3.51 Service Pack 5
    • Microsoft Windows NT 4.0
    • Microsoft Windows 95
    • Microsoft Windows 98 Standard Edition
    • Microsoft Windows 2000 Standard Edition
    • Microsoft Windows Millennium Edition
http://support.microsoft.com/kb/99261

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